1. Field of the Invention
This invention relates to softeners or softening agents for textile finishing. More particularly, the invention relates to a softening agent comprising a quaternary ammonium salt of a specific class.
2. Description of the Prior Art
It has heretofore been known that textile softeners which are used in domestic or home laundering comprise as an essential ingredient a quaternary ammonium salt having in its molecule one or two long-chain alkyl groups. These quaternary-type softeners have the advantage that even when applied in limited amounts, they make it possible to give sufficient softness to natural fibers such as cotton. However, such known quaternary ammonium salts encounter the difficulty that they are not satisfactory for producing softness on synthetic fibers such as acrylics which have recently found wider and better use in the textile industry.
In general, garment fabrics made of synthetic fibers are liable to become gradually stiff during their repeated wearing and washing, and therefore, they require a finishing or softening treatment so as to be rendered suitable for re-wearing without any unpleasant stiffness. In home laundering, almost all kinds of garments are generally washed together in one and the same washing bath. For this reason, a need continues to exist for a textile softening agent capable of affording sufficient softness to both natural fibers and synthetic fibers.
With the above noted difficulties of the existing textile softeners in view, the present inventors have made intensive studies on various softening agents which can satisfactorily impart softness to synthetic fibers, while retaining the same effectiveness or softening action on natural fibers as do conventionally used softeners. In these studies, leading to the invention, it has been found that particular quaternary ammonium salts of formula (I), which will appear hereinafter, achieve the above desired properties and give the best results.